Abstract
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The use of thin GaAsSb capping layers (CLs) is demonstrated to provide InAs/GaAs quantum dot (QD) solar cells (SCs) with improved efficiencies up to 20%. The application of such CLs allows the tunability of the QD ground state, switching the QD-CL band alignment to type II for high Sb contents and extending the photoresponse up to 1.5 ?m. Moreover, the CL provides a significant contribution to the photocurrent. An improved carrier collection efficiency is also found to be a main reason behind the increase of the short-circuit current density, unveiling a negative impact of the wetting layer (WL) on carrier transport in standard InAs/GaAs QD SCs. Calculations from an 8×8 k·p method suggest the attribution of such an improvement to longer carrier lifetimes in the WL-CL structure due to the transition to a type-II band alignment in Sb-containing structures. A faster open-circuit voltage recovery under light concentration is demonstrated for high Sb content type-II QD-CL structures, leading, in turn, to faster efficiency improvements with light power. | |
International
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Si |
Congress
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32nd European Photovoltaic Solar Energy Conference |
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960 |
Place
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Munich (Germany) |
Reviewers
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Si |
ISBN/ISSN
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3-936338-41-8 |
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10.4229/EUPVSEC20162016-1AO.3.3 |
Start Date
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21/06/2016 |
End Date
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24/06/2016 |
From page
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32 |
To page
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35 |
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Proc. 32nd EUPVSEC 2016 |